近年来，随着我国经济的迅速发展，建筑业也得以蓬勃发展，同时也带来了不少工程质量问题，其中地基基础方面的问题占很大比重。已有地基基础加固实践表明，预压桩基础托换法是一种有效的加固方法，当采用基底下钢筋混凝土预压桩基础托换法加固处理后，有的上部结构局部墙体还会出现新的裂缝，从而影响了预压桩基础托换技术的进一步推广及应用。本论文考虑上部结构墙体的受力性能，研究预压桩基础托换法的合理桩间距，具有重要的理论研究意义和工程应用价值。 本文在研究已有地基基础加固理论和工程实践的基础上，结合砖混结构的特点，根据预压桩基础托换法的工艺特点、加固机理及设计要点，分析得出影响加固效果的主要因素包括预压桩桩间距和桩体最大允许沉降量的影响；利用ANSYS有限元分析软件，建立了预压桩合理桩间距的有限元模型，分析了不同桩间距对上部结构墙体受力性能的影响，按上部砖混结构不出现开裂原则，得出不同层数时预压桩的最大桩间距，提出了预压桩合理桩间距计算公式，并研究了单桩沉降量对上部结构墙体受力性能的影响，得出了最大桩间距时的单桩允许最大沉降量；最后结合工程实例验证分析了桩间距计算公式和桩体允许最大沉降量的合理性，表明预压桩基础托换法是一种有效的地基基础加固方法。 上述研究成果可为进一步研究地基基础加固理论与技术，推广和应用预压桩基础托换法有一定的参考价值，也可供类似加固工程设计及施工参考。

In recent years, with the rapid development of China's economy, the construction industry has also flourish. It also brings a lot of quality problems, including the problem of foundation areas account for a large proportion. The foundation that had been reinforced shows that preloading pile foundation underpinning method is an effective method for reinforcing the base when using reinforced concrete pile foundation underpinning preloading method reinforcement, and some of the local upper part wall will appear new cracks, thus affecting the underpinning technology to further the promotion and application preloading piles. This paper considers the mechanical properties of the upper structure of the wall, the study preloading method of pile foundation underpinning reasonable pile spacing has important theoretical significance and application value. In this paper, the main factors in the study based on the existing foundation reinforcement theory and engineering practice, combined with the characteristics of the brick structure. According to the characteristics of preloading pile foundation underpinning method, reinforcement mechanism and design elements,analysis that reinforcing effect of the impact results including pre-press pile spacing and the impact of the maximum allowable settlement pile. Using ANSYS finite element analysis software, established a preload piles Spacing finite element model and analyzed the different pile spacing on the upper wall of the mechanical properties of the structure affected by the principles of upper brick structure is not cracking , derived maximum pile spacing different layers preloading piles, piles made reasonable preload pile spacing is calculated and studied the pile settlement on the wall by the upper structure influence performance, obtained the largest pile of pile spacing to allow maximum settlement amount; Finally analyzed with engineering examples validate pile and pile spacing is calculated to allow a reasonable amount of maximum subsidence, indicating preload pile foundation underpinning method is an effective method of foundation reinforcement. The research results for further research foundation reinforcement theory and technology, promotion and application of preload pile foundation underpinning method has some reference value, but also for engineering design and construction reinforcement similar reference.